Have checked diodes but now feel like an idiot. Both flippers restart machine! I'm sure it used to be just right, but it's been so long I'm not really sure anymore. My next move is to swap the WPC board with my one from TAF which I know works. Does this more accurate reporting of the diagnosis lead anyone to think of an obvious cause? I can't see any shorts. I've had the bridge rectifier, capacitor prob before but this is not like that. It's an instant restart when flippers are hit. I will reset everything with the replacement board as PinWiki suggests, but if you've had this specific issue and think you might know what's going on please let me know. Thanks for all your help so far everyone.